Piston and piston rod assembly



T. R. SMITH PISTON AND PISTON ROD ASSEMBLY original Filed March 13. 194s Sept. 2l, 1948.

Retained sept. 21, 194s Re. 23,041l

UNITED vsf'rlx'ras PATENT 'Ormel-:

PISTN AND PISTON ASSEMBLY Thomas R. Smith, Newton,

.Maytag (Jomnalrn',` of Delaware original No. 2,361,244,

for reissue July 19,

Iowa, as'slgnor to The Newton, Iowa, a corporation dated october 24,1944, serial No. 479,077, March 13, 1943.v

1945, serm No. 605,961

Application 1'1 claims. "tomos-17') The present invention piston rod assembly for-an hydraulic wing ap cylinder and especially to a novel means and manner of assembling a piston on a piston rod wherein the rod extends through and beyond I both the opposite sides or ends ofthe piston.

Among the Aobjects of the present invention isto provide a novell means and manner of assembling a pistonv on an integral or one-piece piston rod extending beyond the opposite sides or ends of the piston and by which the two are quickly lassembled and maintained inaccurate alignrelates to a piston and A further objectl is to provide a novel means l and manner of mounting a piston upon an intermediate portion of a piston rod and maintaining it in assembled relation by means of a spiral key. In this novel arrangement the piston and piston rod are provided or formed with mating spiral grooves,y and a spiral key connects these members together.

Further objects are to provide a construction of maximum simplicity, efficiency, economy and ease of assembly and operation, and such further objects, advantages and capabilities vas will later more fully appear and are inherently possessed thereby.

The invention further resides in the construcv tion, combination and arrangement of parts illustrated in the accompanying drawings, and while there is shown therein a preferred embodiment, it is to be-understood that the same is susceptible of modification and change, and

'1.x these heads are threaded upon the end'ofthe -cylinder and locked thereonby means'oi. anadiustable set screw I.-V To prevent the headfroln becoming disengaged, this set sc rewjis `retained n y in locked position by any In order to seal hydraulic fluid yor voil transferred the heads are each provided with an annular in wardly opening channel in which 'is mounted a resilient sealing ring l of natural .or compounded synthetic suitable means.

which is` adapted to be at all times effecting' optimum'sealin'g'between thesepar'ts. Similarly, 'each head isprovided with an annularv inwardly opening :recess or groove lprovlded with a sealingring vB having a fitting vI3'for'hydrau1ical1y actuating a wing flap comprehends other details, arrangements of parts, features and constructions without departing from the spirit of the invention.

In the drawings:

Figure 1 is a View in side elevation with portions of the cylinder and piston rod broken away.

Figure 2 is an enlarged fragmentary view in vertical cross-section through the cylinder and piston.

Figure 3 is a view in vertical cross-section taken on the line 3 3 of Figure 2.

Figure 4 is a view in side elevation of the spiral key spring.

Figure 5 is a fragmentary view of the piston and piston rod and showing the manner of locking the piston and piston rod in assembled relation.

in the drawings, the embodimenttherein shown to illustrate the present invention comprises a.

cylinder I having a head 2 and a head 3 at its I 50 Referring more particularly to the disclosure continuous sealing contact between the piston rod 9 and the head; Each head is also provided with an opening II) aligned with 'a' passage vI I ventering one end of the cylinder for transferring hydraulic iiuid or oil vfrom a suitable source of ,fluid supply into the opposite ends of the 'cylinder for moving the piston I2 vand piston rod 9 in either desired direction.

In the present embodiment, this piston rod is l provided at its opposite ends with a suitableend of an airplane (not shown).

The present novel invention relates particularly tothe novel pistonandpiston rod assembly in which the piston in assembling a piston and piston vrod wherein the rod extends beyond the opposite ends or` the piston is threaded onto ends of these sections are end or side ofthe piston'.

Where the rod is made in one piecean'd the i piston is threaded thereon, it is necessary to machine approximately the entire length of the rod Ibut leaving suilieient stock at the intermediate 'portion upony which the for threads, or else to threads. This operation is not satisfactory and it is impossible to run these rods over a centerless grinder for high production'due to the fact that there are threads to be ends of the rod.

Where the rod is broken in two or made. in

two sections with the adjacent ends connected,

of the piston, there is always ent. This is also an unsatisto the opposite ends the headagainst leakage Vof "the V to the opposite ends.of1. thecylinder,

rubber or the `likehaving a sealing'- contact with the cylinder adjacentits ends and- I2 is mounted on an inter- 'A mediate portion of the piston rod 9. Ordinarily made into two sections andl piston is to be mounted upsetthis intermediate f portion in order to obtain suiiicient stock for the produced intermediate the l cut into the internal diameter oi' the piston,

' rod assembly together.

sans: f

i'actory method, and these two prior methods, the alignment of the piston on the rod is dependent on the thread. In actual mass production, it has been found impossible to hold sufficiently between the piston and the piston rod so that it is necessary to machine the piston'after it has been assembled on the rod or rods.

In the present novel construction the piston rod 8 is made in one piece and may be run through a centerless grinder. After the rod has Vbeen ground to size, thread grooves il are cut into the piston rod and an annular recess Il is provided at the opposite ends of these threads. The piston Il may be completelydinished before assembling on the rod. with mating grooves Il and when assembled by the novel means and method herein disclosed. the piston and integral piston rod are maintained in accurate alignment. This assembly is accomplished by means of a spiral key I1 which is threaded into the grooves in the piston rod, after which the piston is screwed onto the spiral key.

It will be appreciated that the alignment between the piston and piston rod will be maintained by the hat, accurately machined surfaces between the spiral grooves on these members. Thus the alignment between the piston and piston rod is as accurate as the ht between the ground diameter of the rod and the breached hole of the piston. The spiral key simply prevents the piston from moving back and forth on the rod and does not affect the alignment or concentricity of the piston and piston rod as is the case in the ordinary type thread where the bearing surface occurs on the threads. In this novel construction, arrangement and assembly, the bearing occurs between the piston and the piston rod surfaces radially, and the lateral loads or lengthwise loads are taken by the spiral key.

In order to prevent leakage, litharge and glycerin may be applied when the piston is assembled on the rod, and in order to lock the piston and the opposite ends I., I8 of the ,hub of the piston are swedged into annular grooves or recesses l5. To, facilitate this swedging operation. the ends of the hub are preferably slotted or split as shown Ain Figure 3. In order to prevent leakage between the outer diameter II of the piston and the inner wall 20 of the cylinder, the piston is provided rwith an outwardly opening annular channel 2| in which is provided ya sealing ring 22 extending beyond the circumference o! the piston and adapted at all times to maintain a wiping contact with the interior of the cylinder. 'Ihis sealing member is preferably formed of a resilient material such as a natural or compounded synthetic rubber or other material suitable for the purpose.

Having thus disclosed the invention,

-I claim:

i. A piston and piston rod assembly comprising a piston rod and piston, adapted to beassembled upon the rod intermediate the ends, spiral grooves provided on the rod intermediate its ends. a piston provided with mating grooves, and a spiral key of circular cross section threaded into the grooves of the piston rod after which the piston is threaded onto the spring.

2. A piston and piston rod assembly comprising a piston rod and piston adapted to be assembled upon the rod intermediate its length and whereby the rod extends through the piston and accurate alignment l when assembled in either of nisms connected to the ends loi the rod. mating I grooves provided in the vpiston and on therod intermediate its ends, and a spring threaded into the grooves on the rod and anchored within the mating grooves for connecting the piston and rod and preventing longitudinal movement of the piston upon the rod. l

3. A piston and piston rod assembly compris ing a piston rod having a tting upon its opposite ends, spiral grooves formed on an intermediate portion Yof the rod, a piston formed with an opening having spiral grooves formed in its inner diameter and mating with the grooves formed on the rod, means adapted to be received in the matinggrooves for mounting 'the piston onto the rod, and means for locking the opposite sides of the piston upon the rod.

4. A piston and piston rod assembly comprising a piston rod having a part of uniform cross section and spiral grooves formed on an intermediate portion thereof, a piston provided with an opening having spiral grooves formed in its inner diameter and mating with the grooves formed on the rod, and a spiral key of circular cross section threaded into the grooves o n the piston rod and thereafter adapted to receive the grooves in the piston for connecting the latter onto the rod.

5. A piston and piston rod assembly comprising a piston rod having spiral grooves formed on an intermediate portion thereof, a piston provided with an opening having spiral grooves formed in its inner diameter and mating with the groove formed on the rod, a spiral key spring adapted to -be threaded into the grooves on the piston rod and to receive the grooves in the piston for connecting the latter onto the rod, and meansfor locking the opposite sides of the piston to the piston rod and therebyform a unitary assembly.

6. A piston and piston rod assembly comprising do a piston rod having spiral grooves provided on an intermediate portion thereof, a piston having a hub provided with internal spiral grooves, a spiral key spring adapted to seat within the grooves in the piston and on the rod, and means for locking the opposite ends of the hub upon the piston rod.

7. A piston and piston rod assembly comprising a piston rod having 'spiral grooves provided in an intermediate portion thereof and an annular recess provided at each end of the grooves, a piston having a hub formed with internal spiral grooves, a spiral key spring adapted to seat within the grooves in the piston and rod, and the opposite ends of the hub being swedged into the recesses for locking the piston upon the rod.

8. A piston and pistzn rod assembly comprising a piston rod provided with spiral grooves intermediate its ends and with the rod at the opposite ends of said grooves being of uniform cross section', a piston provided with mating grooves, and a spirally wound key of circular cross section threaded linto and conforming to the grooves of the piston rod after which the piston is threaded onto the key, the piston and rod bearing against each other intermediate the spiral grooves for o and conforming to the mating grooves on the rod beyond its opposite ends for actuating` mecha. 1l after which the piston is threaded onto the key.

' 5 10. Means for connec concentric members comprising an linner member of uniform circular exterior section for a substantial portion-of its length and being helically grooved at anintermcdiate'part only of said portion, the remainder of its length being smooth and the helical groove being of semi-circular cross section, of less length than vided with an inner cylindrical bore having a snug 4rotary ft on the surface of the inner member and being helically grooved for its entire length with its helical groove mating with and of similar cross section as that of the inner member, and a spiral key of circular cross section and of substantially the diameter of the mating grooves mounted in said grooves for retaining the concentric members in accurate alignment.' the surfaces of said members intermediate the 'grooves providing cylindrical abutting surfaces for maintaining alignment. Y

1l. Means for connecting and aligning a pair of concentric members comprising an inner member of uniform circular exterior section for a substantial portion o! its length and being helically .grooved at an intermediate part only ofl said portion and provided with a recess adjacent an end of the groove, the

remainder of its length being an outer concentric member said inner member and pro-` f substantially the diameter of mounted in said grooves for centric members in accurate retaining thereonalignment, the surfaces of said members intermediate the grooves A providing cylindrical abutting surfaces' for main 20 Number smooth and the helical groove being of semicircular cross section. an outer concentric member of less length than said inner member and provided with an `inner cylindrical bore ber and being helically grooved for its entire length with its helical groove mating with and having a snug rotary ilt on the surface of the inner memtaining alignment, and a' projection on the outer member adapted to engage `in the recess of the inner member when said members are in assembled .relation to prevent relative rotation therebetween.

' THOMAS R.'SMI' IH.

REFERENCES crm!) The following references are of record in the ille of this patent: y

UNITED STATES PATENTS Name Date Lipsey May 22, 1883 Greenfield Feb. 1'1, 1903 McMahon Nov. 29, 19a? Ferlin et a1 Jan. 29, 1929 Stevenson Nov. 5, 1935 Staempli A Dec. 3, 1935 Caminez Mar. 14, 1939 Schaefer Mar. 2, 1943 Stinson Feb. 15, 1944 FOREIGN PATENTS Country France Great Britain Date June 16, 1913 Aug. 25, 1921 Number as that of the inner inem` the mating grooves 1 

